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HL: Fachverband Halbleiterphysik

HL 12: 2D Materials I: Electronic Structure, Excitations, etc. (joint session O/CPP/HL)

HL 12.5: Vortrag

Montag, 16. März 2020, 11:45–12:00, WIL C107

Sideband generation & pseudospin-flip excitations in graphene using tr-momentum microscopy — •Marius Keunecke¹, David Schmitt¹, Christina Möller¹, Davood Momeni Pakdehi², Hendrik Nolte¹, Wiebke Bennecke¹, Marie Gutberlet¹, Matthijs Jansen¹, Marcel Reutzel¹, Klaus Pierz², Daniel Steil¹, Hans Werner Schumacher², Sabine Steil¹, and Stefan Mathias¹ — ¹Georg-August-Universität Göttingen. I. Physikalisches Institut, 37077 Göttingen, Germany — ²Physikalisch-Technische Bundesanstalt, Bundesallee 100, 38116 Braunschweig, Germany

The coherent control of quantum states is a promising route towards new emerging phases in solids. One of these phases are the so called Floquet-Bloch states, created by a periodic driving laser. Other light-matter coupled states (Volkov states) arise close to the surface of a solid and are understood as a final state dressing by the laser light. In graphene, the driving by circularly polarized light is predicted to open up a bandgap at the dirac point and thus creating a Floquet topological insulator [1]. In our experiment, the electronic bandstructure of ML graphene on SiC (0001) is mapped during photo-excitation using a momentum microscope in combination with a 1 Mhz femtosecond HHG lightsource (26.6 eV). Different pump wavelengths and polarizations are used to disentangle the excited states dynamics and the sideband generation at high momenta. We will discuss the nature of the generated sidebands and the photoinduced anisotropic hot carrier distributions. [1] M. A. Sentef et al., Nat. Commun. 6, 7047 (2015)